End core design for use as a closure on centrifugal casting molds



Aug. 3, 1965 Filed Dec. 1, 1961 P. F. HAUGHTON ETAL END CORE DESIGN FORUSE AS A CLOSURE ON CENTRIFUGAL CASTING MOLDS 2 Sheets-Sheet l mlmnINVENTORS. PAUL F. HAUGHTON JAMES H. ESPY 1965 P. F. HAUGHTON ETAL3,197,827

END CORE DESIGN FOR USE AS A CLOSURE 0N CENTRIFUGAL CASTING MOLDS FiledDec. 1. 1961 2 Sheets-Sheet 2 FIG. 4

INVENTORS PAUL E HAUGHTON JAMES H. ESPY United States Patent 3,197,827END CURE DESIGN FOR USE AS A CLOSURE ON CENTRIFUGAL CASTING MGLDS PaulF. Haughton, Ringgold, Ga., and James H. Espy,

Chattanooga, Tenn., assignors to Combustion Engineering, Inc., Windsor,Conn., a corporation of Delaware Filed Dec. 1, 1961, Ser. No. 156,225 7Claims. (Cl. 22-1135) This invention relates to apparatus for thecentrifugal casting of metal, and in particular to a new end core designto be used on the rotating mold of the casting apparatus.

One method used today for making metal tubing or pipes is tocentrifugally cast hollow cylindrical. castings,

by pouring a molten metal into a mold rotating at high speeds. The innerand outer diameters of the so-formed castings are then machined to formsmooth, flawless cylindrical surfaces. These machined pieces can then bepassed through a reducing machine which will reduce the diameter of suchpieces, thereby extending the length if desired.

In casting molten metal in a rotating mold, some means must be providedfor preventing themolten metal from running out the ends of the mold.For this purpose, an end core is generally secured to each end of themold. However, the end cores presently being used today do not entirelynor satisfactorily prevent run out from the mold ends, and due to thisrun out of molten metal, the end portions of the casting are in manyinstances inrperfect, requiring the ends of such castings to be cut off,or heavy grinding is required to eliminate the flaws. It is an object ofthis invention to provide a new end core design having configurations orirregularities formed on the surface of the end core which comes incontact with the molten metal, which will impel the molten metalradially outwardly into contact with the mold, which makes the moltenmetal spin with the mold, thus retarding or preventing run out from themold ends.

Other objects and advantages will become apparent from the followingdescription taken in conjunction With the accompanying drawings wherein:

FIGURE 1 is a side view of a centrifugal casting apparatus on which ournew end core is utilized;

FIGURE 2 is an enlarged cross sectionalview showing the end core securedto the mold;

FIGURE 3 is a perspective of the end core of our invention;

FIGURE 4 is a perspective of a second embodiment of an end core;

FIGURE 5 is a perspective of a third embodiment of an end core.

Looking now to FIGURE 1 of the drawings, numeral designates a mold tobeused for the centrifugal casting of hollow cylindrical metalliccastings. This mold is rotated during the casting process by means of amotor 14, which rotates rollers or bearings 22 and 24 secured on shaftby means of drum 16 and belt 18. Members 26 and 28 which are fixed orsecured in any suitable manner support the rotating shaft 20. The otherside of the rotating mold is similarly supported by rollers or bearingswhich are not driven.

The left and right ends of mold 10 contain flanges 36 and 38respectively, and end cores 40 and 46 are removably secured, for exampleby securing or retaining rings 42 and 48 which are bolted by means ofbolts 44 and 50, to the flanges during the casting process to preventthe molten metal from being spun out of the ends of mold 10.

Molten metal which is melted in an electric induction furnace (notshown) is transferred from pouring ladle into boot 32 and flows fromboot 32 into the hollow 3,197,827 Patented Aug. 3, 1965 "ice 1 and 2, athin layer of a suitable lining material 12,

for example a mixture of diatomaceous earth containing a smallpercentage of bentonite clay as a binder, is formed on the inner surfaceof mold 10 to prevent the molten metal being cast from coming in contactwith and becoming fused to the mold 10. This lining material mustcompletely cover the inner surface of mold 10 for if the molten metalwere to come in contact with mold 10 even in a few small spots, thefusion formed thereby would be suflicient to prevent the later removalof the casting from the mold. After the casting has been allowed to cooland solidify, end core 40 is removed to permit the casting to be pulledout of the mold.

FIGURES 2 and 3 illustrate one embodiment of our new end core design,containing equally spaced protrusions 62 which extend radially outwardfrom the central opening of the end core a predetermined distance. Asthe molten metal runs down the length of the mold 10 and comes intocontact with the end core 48, a portion of such molten metal will tendto flow downwardly along the surface of end core 40 and eventually runout of the mold through central opening 60 illustrated in FIGURE 2. Themolten metal which tends to run down along the surface of end core 40comes into contact with equally spaced, radial protrusions 62 beforereaching central opening 60, and such protrusions on the rotating endcore 40 will throw the molten metal outwardly, acting in the same manneras a pump impeller thereby centrifugally pumping such molten metalradially outwardly into contact with the inner wall of the rotatingmold, where it will again frictionally engage such wall and thus rotateor spin with the mold 10.

FIGURE 4 illustrates a second embodiment of our invention whereby theend core is provided with equally spaced indentations 70, which extendradially outward from the central opening. FIGURE 5 shows a thirdembodiment which utilizes equally spaced indentations which extendoutwardly at an angle to radial lines from the central opening of theend core. The indentations 70 and 80 formed in theend cores shown inFIG- URES 4 and 5 perform in the same manner as the protrusions 62 ofthe FIGURE 3 embodiment, acting as a pump impeller to throw the moltenmetal outwardly as it runs down the surface of the end core.

The size and number of protrusions or indentations utilized on the endcore isnot critical, so long as there are enough and they are ofsufiicient size to act as a pump impeller thereby causing the moltenmetal coming in contact therewith to be thrown outwardly against theinner Wall of the mold, thus causing it to spin with the mold. The endcore can be made of any suitable refractory material and by suchstandard methods as shell molding, CO process or the like which haveproven satisfactory for such use. As illustrated in FIGURE 1, both theleft and right end cores have central openings therein. It is necessaryto provide a central opening in the left end core 46 to allow insertionof the pouring spout 34 into the interior of mold 10. The reason thecentral opening is provided in the right end core 40 is to permit thegases generated during the casting process to escape from the mold 10.It would be possible to omit the opening in right end core 49 shown inFIGURE 1, thereby forcing the gases to double back within the mold 10and escape from the central opening in the end core position on thepouring or left end. But such-gases would tend to carry some of themolten metal along with it out of the mold, and for this reason it ismore desirable to provide a central opening in the end core at bothends.

3% The size of the central opening in the end core is not critical,although it must not be larger than the internal diameter of the castingbeing poured.

As mentioned earlier the irregularities, either protrusions orindentations, formed on the end cores prevent the molten metal as it isbeing poured from running out of the ends of the mold. As an example ofthe effectiveness of these cores, the design shown in FIGURE 3 was usedin making a casting with a 2 /3" internal diameter, and the centralopening in the end core was also 2%". The molten metal spun out of themold was found to be less than one pound. When castings having 2 /3"inner diameters were poured using a core with a smooth surface, havingacentral opening 2 /8" in diameter, as much as 20 pounds would spin orrun out of the mold under similar casting conditions. When large amountsof molten metal run out the mold ends, the end portions of the castingare generally imperfect and require either heavy grinding or else aportion of the ends must be removed from the casting. It should bepointed out that the smaller the diameter of the mold, and the thickerthe casting wall, the more advantage there is in using our end coredesign. This is because there will be less centrifugal force tending toprevent the molten metal flowing towards the end core central opening. e

The end core of our invent-ion could be used in centrifugally castingmaterials other than metal, for example certain types of plastics whererun out from the ends of the mold is a problem. Irregularities on thesurface of the end core might also be of value even though there is nocentral opening in the end core. Such irregularities would still tend tocause the molten metal coming into contact therewith to be pumped orimpelled radially outwardly against the inner mold wall, and thus theywould prevent any metal from running down into the center of the moldnear the mold end. While We have shown and described the preferredembodiments of the invention it is to be understood that the inventionis not limited thereto but may be otherwise variously embodied andpracticed within the scope of the following claims.

What we claim is:

1. Apparatus to be used for centrifugal casting including asubstantially horizontally positioned hollow cylindrical mold, said moldhaving a first pouring end and a second nonpouring end, meansforrotating the mold, means for introducing a molten material into the moldthrough the first end, an end core secured to the second end,irregularities on the surface of the second end core which comes incontact with the molten material being cast, said irregularities beingpositioned such, and being of such configuration that they act as a pumpimpeller while the mold and end core are rotating to give the moltenmaterial which tends to run down the end core surfaces additional spin.

2. The apparatus set forth in claim 1, wherein said irregularities areprotrusions on the surface.

3. The apparatus set forth in claim 1, wherein said irregularities areindentations on the surface.

4. Apparatus to be used for centrifugal casting including asubstantially horizontally positioned hollow cylindrical mold, said moldhaving a firstend and a second end, means for rotating the mold, meansfor introducing a molten material into the mold, which molten materialwill flow longitudinally in the mold, a firstend core se cured to thefirst end, a second end core secured to the second end, said first andsecond end cores each having means forming a central opening therein,said first and second end cores also having irregularities on thesurface of each Whichcomes in contact with the molten material beingcast, the irregularities being positioned such, and being of suchconfiguration that they act as pump impellers while the mold and endcores are rotating to give the molten material which tends to .run downthe end core surfaces additional spin.

5. The apparatus set forth in claim 4, wherein the irregularities are aplurality of protrusions on the end core surf-aces which extend radiallyoutwardly a distance from the central openings.

6. The apparatus set forth in claim 4, wherein the irregularities are aplurality of indentations on the end core surfaces which extend radiallyoutwardly a distance from the central openings.

7. The apparatus set forth in claim 4, wherein the irregularities on theend core surfaces are a plurality of indentations which extend outwardlyat an angle to radial lines from the central openings. 9

References Cited by the Examiner UNITED STATES PATENTS 1,161,701' 11/15Le May 22-65 1,944,461 1/34 Pike 22-2005 2,090,289 8/37 Fretz 22-11352,745,152 5/56 Johnson 22-65 2,770,857 11/56 Boissou 22-65 WILLIAM J.STEPHENSON, Primary Examiner.

MARCUS ;U. LYONS, ROBERT F. WHITE, MICHAEL V. BRINDISI, Examiners;

1. APPARATUS TO BE USED FOR CENTRIFUGAL CASTING INCLUDING ASUBSTANTIALLY HORIZONTALLY POSITIONED HOLLOW CYLINDRICAL MOLD, SAID MOLDHAVING A FIRST POURING END AND A SECOND NONPOURING END, MEANS FORROTATING THE MOLD, MEANS FOR INTRODUCING A MOLTEN MATERIAL INTO THE MOLDTHROUGH THE FIRST END, AN END CORE SECURED TO THE SECOND END,IRREGULARITIES ON THE SURFACE OF THE SECOND END CORE WHICH COMES INCONTACT WITH THE MOLTEN MATERIAL BEING CAST, SAID IRREGULARITIES BEINGPOSITIONED SUCH, AND BEING OF SUCH CONFIGURATION THAT THEY ACT AS APLUMP IMPELLOR WHILE THE MOLD AND END CORE ARE ROTATING TO GIVE THEMOLTEN MATERIAL WHICH TENDS TO RUN DOWN CORE SURFACE FACES ADDITIONALSPIN.